U2AF1 and myelodysplastic syndrome: Recent studies have demonstrated that MDS and AML cells bearing mutations in RNA spliceosome components including SF3B1, SRSF2 and U2AF1 are preferentially sensitive to spliceosome inhibition (Fei et al., 2016; Lee et al., 2016; Obeng et al., 2016; Shirai et al., 2017).